FIG. 6 shows a procedure of a general OPC of a disk recording/reproducing apparatus which irradiates an optical laser beam from an optical head and varies a reflectance of a recording layer of a disk to perform a recording operation. As shown in FIG. 6, first, while a recording power of the optical laser beam is varied on a test recording area of the disk stepwise, for example, by fifteen steps, a test recording operation (test writing of data) is performed (first step). Next, an RF signal is reproduced and sampled while the test recording area (an area to which the test writing operation is performed) is read again (second step), a recording state index value (for example, β (asymmetry)) which represents an index of a recording state is calculated from the sampled RF signal (third step), and a value closest to a target value is selected out of the calculated recording state index values and a power corresponding thereto is selected as an optimum recording power, thereby determining the optimum power of the laser beam irradiated in recording operation (fourth step).
However, recently, recording media become diversified with increase in writing speed, decrease in price and the like, and there are deviations in media quality and characteristic of apparatuses. Accordingly, even if a power is varied stepwise at the time of performing the general OPC, the recording state index value which can be obtained is not always changed uniformly. In this case, the optimum recording power may be not accurately acquired or an improper recording power may be acquired. When a recording operation is performed with an inaccurate optimum recording power, there occurs a problem that a recording quality is deteriorated, thereby not reading the recorded data.
As a known method solving such a problem, there is disclosed a method in which the test recording area is reproduced, the recording state index value is acquired, powers P1 and P2 of a point on which the acquired recording state index value is varied from large to small and a point on which the acquired recording state index value is varied again from small to large are acquired, and an average of the powers P1 and P2 is given as the optimum recording power (for example, see (Paragraphs 7 to 14 and FIG. 2) of Patent Document 1 (JP-A-9-180193)).
As another known method, there is disclosed a method in which an unrecorded area is reproduced prior to a recording operation, a scratch or a fingerprint of the disk is detected, and a corresponding point is skipped in OPC when the scratch or the fingerprint is detected (Paragraphs 5 to 7 and FIG. 9) of (for example, see Patent Document 2 (JP-A-2002-319135).